The AstroBID: preserving and sharing the Italian astronomical heritage

The cultural heritage of the National Institute for Astrophysics (INAF), made of rare and modern Books, Instruments and archival Documents, the AstroBID, marks the milestones in the history of astronomy in Italy. INAF, in collaboration with the Department of Physics and Astronomy of the University of Bologna, has developed a project to preserve, digitize, and valorize its patrimony by creating a web portal Polvere di Stelle. It shows the cultural heritage of 12 libraries and historical archives, and 13 instrument collections, and allows both academics and a wider audience to search simultaneously the AstroBID materials

Testing the improvement of ShakeMaps using f inite-f ault models and synthetic seismograms

ShakeMap package uses empirical ground motion prediction equations (GM PEs) to estimate the ground motion where recorded data are not available. Recorded and estimated values are then interpolated in order to produce a shaking map associated to the considered event. Anyway GMPEs account only for average characteristics of source and wave propagation processes. Within the framework of the DPC-INGV S3 project (2007-09), we evaluate whether the inclusion of directivity effects in GMPEs (companion paper Spagnuolo et al., 2010) or the use of synthetic seismograms from finite-fault rupture models may improve the ShakeMap evaluation. An advantage of using simulated motions from kinematic rupture models is that source effects, as rupture directivity, are directly included in the synthetics. This is particularly interesting in Italy where the regional GMPEs, based on a few number of near-source records for moderate-to-large earthquakes, are not reliable for estimating ground motion in the vicinity of the source. In this work we investigated how and if the synthetic seismograms generated with finite-fault models can be used in place of (or in addition to) GMPEs within the ShakeMap methodology. We assumed a description of the rupture model with gradually increasing details, from a simple point source to a kinematic rupture history obtained from inversion of strong-motion data. According to the available information synthetic seismograms are calculated with methods that account for the different degree of approximation in source properties. We chose the M w 6.9 2008 Iwate-M iyagi (Japan) earthquake as a case study. This earthquake has been recorded by a very large number of stations and the corresponding ShakeMap relies almost totally on the recorded ground motions. Starting from this ideal case, we removed a number of stations in order to evaluate the deviations from the reference map and the sensitivity of the map to the number of stations used. The removed data are then substituted with synthetic values calculated assuming different source approximations, and the resulting maps are compared to the original ones (containing observed data only). The use of synthetic seismograms computed for finite-fault rupture models produces, in general, an improvement of the calculated ShakeMaps, especially when synthetics are used to integrate real data. When real data are not available and ShakeMap is estimated using GMPEs only, the improvement adding simulated values depends on the considered strong-motion parameters

Starlight. La nascita dell'astrofisica in Italia / The origins of astrophysics in Italy

Starlight è una mostra a rete, con cinque sezioni dislocate in cinque osservatori diversi, raccordati virtualmente tramite l'omonima mostra virtuale bilingue. E' stata il prodotto finale del progetto "Analyzing starlight", finanziato da INAF con PDIN 2014, che include anche il catalogo cartaceo e la versione online della mostra. Le cinque sezioni sono così costituite: 1. Le origini dell'astrofisica a Firenze (sede: INAF-Osservatorio Astrofisico di Arcetri, Firenze); 2. Roma, capitale dell'astrofisica (sede: INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone); 3. L'eclisse totale di sole del 1870 (sede: INAF-Osservatorio Astronomico di Capodimonte, Napoli); 4. Lo sviluppo della fisica solare (sede: Chiesa di S. Maria delle Grazie, Palazzo dei Normanni, Palermo); 5. Una società scientifica italiana per l'astrofisica (sede: INAF-Osservatorio Astronomico di Padova

The EU Center of Excellence for Exascale in Solid Earth (ChEESE): Implementation, results, and roadmap for the second phase

publishedVersio

Joint inversion of GPS and strong motion data for earthquake rupture models

Ricostruzione del processo di rottura cosismico su faglia finita attraverso l’inversione congiunta di dati sismologici e geodetici. Implementazione e validazione di una nuova tecnica di inversione non lineare, di tipo global search, per l’inversione congiunta di dati GPS e dati strong motion. Analisi statistica dell’ensemble dei modelli di rottura esplorati dall’algoritmo di inversione. Analisi sulla consistenza dinamica dei modelli cinematici di rottura. Applicazioni: (1) Test Sintetici atti a validare la capacità di risoluzione e robustezza della tecnica sviluppata; (2) Analisi del terremoto di Tottori (2000); (3) Analisi del terremoto di Niigata (2007); (4) Determinazione di scenari di scuotimento in aree di interesse prioritario e strategico (terremoto dell’Irpinia, 1980).Istituto Nazionale di Geofisica e VulcanologiaUnpublished3.1. Fisica dei terremotiope

Urania digitale: il patrimonio storico scientifico degli osservatori astronomici italiani in Polvere di stelle e Internet Culturale

L’Istituto Nazionale di Astrofisica (INAF), il principale ente di ricerca italiano per lo studio dell’Universo, promuove, realizza e coordina attività di ricerca nei campi dell’astronomia e dell’astrofisica. Inoltre progetta e sviluppa tecnologie innovative e strumentazione d’avanguardia per lo studio e l’esplorazione del cosmo. È costituito da 19 strutture distribuite sul territorio nazionale, alcune delle quali di antica fondazione. Gli osservatori astronomici possiedono infatti un cospicuo patrimonio storico, bibliografico e archivistico che costituisce un unicum di grande interesse culturale nell’ambito degli entidi ricerca italiani ed europei. Da qualche anno è in corso un progetto complessivo di tutela e valorizzazione che ha condotto anche alla scelta di digitalizzare i volumi e le carte di archivio più significativi sia da un punto di vista culturale sia da un punto di vista iconografico. Le digitalizzazioni compiute sono a disposizione sul portale dei beni culturali dell’INAF “Polvere di stelle” dove è possibile sfogliare integralmente i volumi e consultare una scelta di documenti provenienti dagli archivi storici, in particolar modo osservazioni solari, stellari e meteorologiche fatte nel corso del XIX secolo. Inoltre dello stesso materiale bibliografico e archivistico sono state realizzate scansioni ad alta risoluzione conservate presso il repository nazionale di INAF(Italian data center for astronomical archives) utilizzando gli stessi criteri di storage e sharing riservato ai dati astronomici. Grazie alla collaborazione di ICCU, dal 2019 è possibile consultare tali collezioni digitali con Internet Culturale ed European

Investigating the effectiveness of rupture directivity during the August 24, 2016 Mw 6.0 central Italy earthquake

In this study we investigate directivity effects associated to the Mw6.0 Amatrice earthquake taking into account the source rupture heterogeneities. We use the directivity predictor proposed by Spudich et al. (2004) which is derived from the isochrones theory. The directivity is computed using a source to site geometry and a focal mechanism. For its simplicity it can be computed once that a moment tensor solution is available. We use this technique to validate the real time solutions. Moreover, because the directivity predictor depends on the rupture velocity it can be used as a proxy to validate the possible rupture history. For the aforementioned reasons our method revealed fruitful for real time applications and helpful to constrain a few main rupture features for further analysis

Rupture Kinematics and Structural‐Rheological Control of the 2016 Mw 6.1 Amatrice (Central Italy) Earthquake From Joint Inversion of Seismic and Geodetic Data

We investigate the rupture process of the 2016, Mw6.1 Amatrice earthquake, the first shock of a seismic sequence characterized by three damaging earthquakes occurred in Central Italy between August and October. We jointly invert strong motion, High-Rate GPS data, GPS and DInSAR displacements and we adopt ad-hoc velocity profiles of the crust below each station. The retrieved source model reveals a high degree of complexity, characterized by a prominent bi-lateral rupture with low slip at the hypocentre, two well-separated slip patches and a rupture front accelerating when breaking the largest patch. The rupture of the main asperity features a slip-velocity pulse that is impeded ahead of its current direction and splits into two pulses. In this fault section we find clues of structural and rheological control of the rupture propagation due to the fault system segmentation.Published12302-123113T. Sorgente sismicaJCR Journa

Variability in synthetic earthquake ground motions caused by source variability and errors in wave propagation models

Numerical simulations of earthquake ground motions are used both to anticipate the effects of hypothetical earthquakes by forward simulation and to infer the behaviour of the real earthquake source ruptures by the inversion of recorded ground motions. In either application it is necessary to assume some Earth structure that is necessarily inaccurate and to use a computational method that is also inaccurate for simulating the wavefield Green’s functions. We refer to these two sources of error as ‘propagation inaccuracies’,whichmight be considered to be epistemic.We show that the variance of the Fourier spectrum of the synthetic earthquake seismograms caused by propagation inaccuracies is related to the spatial covariance on the rupture surface of errors in the computed Green’s functions, which we estimate for the case of the 2009 L’Aquila, Italy, earthquake by comparing erroneous computed Green’s functions with observed L’Aquila aftershock seismograms (empirical Green’s functions). We further show that the variance of the synthetic seismograms caused by the rupture variability (aleatory uncertainty) is related to the spatial covariance on the rupture surface of aleatory variations in the rupture model, and we investigate the effect of correlated variations in Green’s function errors and variations in rupture models. Thus, we completely characterize the variability of synthetic earthquake seismograms induced by errors in propagation and variability in the rupture behaviour. We calculate the spectra of the variance of the ground motions of the L’Aquila main shock caused by propagation inaccuracies for two specific broad-band stations, the AQU and the FIAM stations. These variances are distressingly large, being comparable or in some cases exceeding the data amplitudes, suggesting that the best-fitting L’Aquila rupture model significantly overfits the data and might be seriously in error. If these computed variances are typical, the accuracy of many other rupture models for past earthquakes may need to be reconsidered. The results of this work might be useful in seismic hazard estimation because the variability of the computed ground motion, caused both by propagation inaccuracies and variations in the rupturemodel, can be computed directly, not requiring laborious consideration of multiple Earth structures

Analysis of the variability in ground-motion synthesis and inversion

U.S. Geological SurveyPublished2T. Sorgente Sismic